A rigid flex circuit board includes a combination of rigid circuit portions and flexible circuits that form a single, electrically interconnected structure. The rigid circuit board incorporates two printed circuit boards (PCBs) that act as external layers, making the rigid circuit board a rigid structure with an inner flexible layer. In the flexible circuits, the two external PCBs included in the rigid circuit boards are cut away leaving the inner flexible layer as a flexible structure.
The flexible circuit typically protrudes from the edge of the rigid circuit board, maintaining the electrical interconnection between the rigid circuit board and flexible circuit. Such designs are space-inefficient as the flexible circuit prevents dense abutment of a second rigid flex circuit board. Other designs attempt to minimize the space occupied by the circuit board by connecting the flexible circuit to the top surface of the rigid circuit board. The flexible circuit maintains the electrical interconnection with the rigid circuit board via a connector placed on the top surface of the rigid circuit board. For small rigid circuit boards, finding an appropriately sized connector is difficult and/or increases the cost of the circuit board.